Last Friday, striking ground workers at Berlin's Tegel and Schöenefeld airports led to the cancellation of nearly all flights in—and out—of the German capital, capping off Europe's worst week of travel disruptions in 2017: Finnair also canceled 104 flights on Friday because of a service staff strike, and air traffic controllers in France protested through the duration of last week, affecting more than 1,500 flights, according to Bloomberg.

Yet the strikes, protests, delays, and cancellations are far from over. Ground staff at Berlin's airports on Monday morning began a 25-hour strike, and Ver.di, a large German trade union, has warned more are on the way. Italian airport employees have said they will walk out on March 20 and April 21, and some Alitalia employees have planned a 24-hour strike for April 5, while Finnish airport workers have other strike dates in the works for the end of March. French air traffic controllers—the worst offenders in Europe when it comes to striking—set a record in 2016 for number of days affected, and seem to be continuing the pattern in 2017 due to their long-running dispute with the government over pensions, pay, and job security.

European airports and unions are not alone in their strikes, either: On November 29 of last year, as Traveler's Barbara Peterson and Sebastian Modak previously reported, baggage handlers, aircraft cleaning crews, and hundreds of other airport contract workers walked off the job at Chicago O’Hare and protested outside of the terminal buildings. Workers at Reagan National Airport outside Washington, D.C., Newark Liberty Airport, Boston Logan, and other major U.S. airports also staged protests. (No flights were canceled.) But when it comes to strikes, why are they more frequent at European airports—and on European airlines?

Labor laws, for one. In France, for example, union protections make it difficult for companies to fire workers, enabling them to repeatedly strike without consequence. Comparably, in the U.S., union memberships have shrunk steadily in the past 50 years, and today, only 10.7 percent of wage and salary workers in the U.S. are in unions, making it difficult for many to strike without fear of being fired. New Zealand, Germany, Australia, and France have also turned their air traffic control over to independent or nonprofit corporations, and it is not illegal—as it is in the U.S.—for controllers to walk off the job. It's much of the same story for U.S. airlines, who are bound by the Railway Labor Act: In order to even be allowed to strike, airline employees must get the National Mediation Board (NMB), responsible for airline labor negotiations, to grant unions the right. Given the disruption a strike can have on an airline's pocket change, the NMB is reluctant to do so. (The last approved strike was for Spirit pilots in 2010, after more than three years of back-and-forth.)

Unfortunately, even though U.S. and European airlines have stipulations in place for flight cancellations, labor strikes fall under "extraordinary circumstances," meaning carriers are not entitled to offer travelers compensation—oftentimes, their obligation ends at getting you to your destination as soon as possible. Traveling to Europe in the coming months? If you can, look to avoid airports and airlines with active labor disputes—Lufthansa pilots and British Airways flight crew are two recent examples—or look into travel insurance that covers cancellations due to strikes. If a strike happens while you're at a destination, hop on the phone for the fastest service, look to an airline's alliance partners, or wait it out—European strikes typically only last for a few days.